1. Field of the Invention
The present invention relates to a two-stage movement seesaw switch apparatus which is preferably used as a switch for a power window of an automobile, for example, and outputs a first-stage electric signal and a second-stage electric signal in response to a tilting angle of a tiltably supported manipulation knob.
2. Description of the Related Art
As this type of two-stage movement seesaw switch apparatus, conventionally, there has been proposed a switch apparatus which includes a manipulation knob which is tiltably supported, a pair of operation plates to which a pushing force is applied from the manipulation knob by way of drivers, and two sets of push switches each made up of two push switches (that is, four push switches) which support the respective operation plates, wherein one operation plate is driven by pushing and is tilted in response to the tilting direction of the manipulation knob and the push switch is operated by the tilted operation plate (see Patent Reference 1, for example). In such a conventional seesaw switch apparatus, each set of pushing switches made up of two push switches are arranged at positions whose distances to the tilting center line of the manipulation knob differ, and a straight line which connects both push switches obliquely intersects the tilting center line and, at the same time, two opposing corners of the operation plate having an approximately parallelogram in a plan view are supported on both push switches, whereby these two push switches are sequentially operated in response to the tilting angle of the manipulation knob.
That is, when a manipulator performs tilting manipulation of the manipulation knob so as to lower one side of the manipulation knob, a driver which is positioned below one side is pushed and descends, and the corresponding operation plate is tilted using the push switch close to the tilting center line of the manipulation knob as a fulcrum and hence, the push switch which is away from the tilting center line is pushed by the operation plate and performs an ON operation. In this state, when the manipulation knob is further tilted and the driver further descends, the operation plate is tilted using the push switch in the ON state which is away from the tilting center line as a fulcrum this time and hence, the push switch which is close to the tilting center line is pushed by the operation plate and performs the ON operation. Further, when the arbitrary push switch is made to perform the ON operation and, thereafter, the manipulation force applied to the manipulation knob is released, the operation plate is pushed upwardly due to a restoring force of the push switch which is pushed by the operation plate and hence, the manipulation knob is pushed back to a neutral position and the push switch restores the OFF state. Here, in this conventional proposal, each of the push switches is constituted of a fixed contact arranged on a board and a click rubber having a movable contact which is brought into contact with and is separated from the fixed contact and is capable of performing buckling deformation. The push switch is configured such that the operation plate is supported on a top of the click rubber and when the click rubber is pushed by the operation plate and performs the buckling deformation at the time of manipulation, the movable contact and the fixed contact are brought into contact with each other while generating a click feeling.
In such a conventional two-stage movement seesaw switch apparatus, it is possible to arrange four push switches in a relatively compact manner and the push switches exhibit a favorable manipulation feeling and hence, the switches are suitable as power window switches of an automobile or the like. In this case, two push switches which are operated by one operating plate output electric signals to open windows and remaining two push switches which are operated by another operating plate output electric signals to close the windows. Further, the two-stage movement seesaw switch apparatus may be configured such that the opening signals and the closing signals of the push switches which are away from the tilting center line of the manipulation knob are outputted only during the ON operation, while the push switches which are close to the tilting center line of the manipulation knob output the signals which make the windows completely open or completely close during the ON operation. Due to such a constitution, the manipulator can perform the manual operation to open or close the windows by an arbitrary amount by tilting the manipulation knob with a shallow angle and can perform an automatic operation to make the window fully open or fully close by tilting the manipulation knob with a deep angle.
[Patent Reference 1]
U.S. Pat. No. 5,693,920
The above-mentioned two-stage movement seesaw switch apparatus has succeeded in making the switch apparatus compact to some extent by providing the idea that the straight line which connects one set of push switches made up of two push switches is made to obliquely intersect the tilting center line of the manipulation knob. However, it is difficult for the switching apparatus to satisfy further miniaturization of the device and further reduction of cost derived from reduction of the number of parts.
The present invention has been made in view of the above-mentioned circumstances and it is an object of the present invention to provide a two-stage movement seesaw switch apparatus which can facilitate the miniaturization of the device and the lowering of cost.
To achieve the above-mentioned object, a two-stage movement seesaw switch apparatus of the present invention is constituted such that the switch apparatus includes a manipulation knob which is tiltably supported, a pair of drivers corresponding to a tilting direction of the manipulation knob, an operation plate which is pushed and driven by the manipulation knob by way of the drivers, a first push switch and a second push switch which support both ends of the operation plate, and a third push switch which is arranged at a position displaced from a straight line which connects both push switches and supports an intermediate portion of the operation plate, wherein one of the drivers imparts a pushing force from the manipulation knob to a portion of the operation plate closer to the first push switch than the third push switch so as to make the operation plate sequentially operate the first push switch and the third push switch in response to a descending amount of the driver, and another of the drivers imparts a pushing force from the manipulation knob to a portion of the operation plate closer to the second push switch than the third push switch so as to make the operation plate sequentially operate the second push switch and the third push switch in response to the descending amount of the driver.
In the seesaw switch apparatus having such a constitution, when the manipulation knob is tiltably manipulated, one of the drivers descends and imparts the pushing force from the manipulation knob to the portion close to one end or another end of the operation plate. For example, when the pushing force from the manipulation knob is imparted to the portion of the operation plate closer to the first push switch than the third push switch due to the tilting manipulation of the manipulation knob, the operation plate is, first of all, tilted using the third push switch as a fulcrum and hence, the first push switch performs the ON operation. When the manipulation knob is further tilted in this state, this time, the operation plate is tilted using the first push switch held in the ON state as a fulcrum so that the third push switch performs the ON operation. Here, since the third push switch is arranged at the position displaced from the straight line which connects the first push switch and the second push switch, the pushing force from the manipulation knob is hardly applied to the second push switch and there is no possibility that the second push switch performs the ON operation. Further, when the manipulation knob is tiltably manipulated in the reverse direction so as to make the driver impart the pushing force from the manipulating knob to the portion of the operation plate closer to the second push switch than the third push switch, in the same manner as the above-mentioned operation, first of all, the operation plate is tilted using the third push switch as a fulcrum so that the second push switch performs the ON operation. When the manipulation knob is further tilted in this state, the operation plate is tilted using the second push switch as a fulcrum so that the third push switch performs the ON operation. Here, due to the same reason as the above-mentioned operation, the pushing force from the manipulation knob is hardly applied to the first push switch and hence, there is no possibility that the first push switch performs the ON operation. Accordingly, using three push switches which are driven by pushing the common operation plate, it is possible to take out four types of electric signals, namely the signal which is outputted when only the first push switch assumes the ON state, the signal which is outputted when both of the first and the third push switches assume the ON state, the signal which is outputted only when the second push switch assumes the ON state, and the signal which is outputted when both of the second and the third push switches assume the ON state. That is, the seesaw switch apparatus which is capable of outputting four types of electric signals in response to the tilting direction and the tilting angle of the manipulation knob can be realized using a small number of parts and hence, the number of the push switches and the operation plate can be reduced whereby the miniaturization can be facilitated.
According to the two-stage movement seesaw switch apparatus of the present invention, in addition to the above-mentioned constitution, the operation plate is formed in an approximately L-shape in a plan view and includes a bend which is supported by the third push switch as well as a first extension and a second extension which extend from the bend in a truncated chevron shape, wherein a distal end of the first extension is supported by the first push switch and a distal end of the second extension is supported by the second push switch. In this case, it is possible to easily ensure a space which faces a bottom face of the manipulation knob in an opposed manner between the first extension and the second extension of the operation plate and hence, by providing an illuminator which is exposed to the space in a projecting manner at a side of the third push switch, it is possible to realize without difficulty the two-stage seesaw switch apparatus of an illumination type.
Further, the operation plate having an approximately L-shape in a plan view may include a first resilient portion which connects the bend with the first extension, a first pushing force transmission portion which is projected from the first extension to the bend side and pushes the bend when the first extension is tilted using the first push switch as a fulcrum due to the pushing force of the manipulation knob, a second resilient portion which connects the bend with the second extension, and a second pushing force transmission portion which is projected from the second extension to the bend side and pushes the bend when the second extension is tilted using the second push switch as a fulcrum due to the pushing force of the manipulation knob. In this case, compared to a case where the operation plate formed of a single sheet of plate is used, a risk that respective push switches are erroneously operated is significantly decreased. That is, when the first extension is tilted using the third push switch as a fulcrum due to the pushing force from the manipulation knob, the first resilient portion is resiliently deformed and hence, the pushing force from the manipulation knob is hardly transmitted to the bend whereby there is no possibility that the third push switch is erroneously operated when the first push switch is operated. Further, when the first extension is tilted using the first push switch held in the ON operation as a fulcrum, the bend is surely pushed by the first pushing force transmission portion so that the third push switch can be operated and, at the same time, since the second resilient portion receives the resilient deformation, the pushing force from the manipulating knob is hardly transmitted to the distal end of the second extension. Accordingly, there is no possibility that the second push switch is erroneously operated. Here, these operations in series are basically performed in the same manner in tilting the second extension.
Further, each of the push switches may include a fixed contact and a click rubber which is provided with a movable contact which is brought into contact with or is separated from the fixed contact and is capable of performing the buckling deformation, and a top of the click rubber engages with the operation plate. Due to such a constitution, it is possible to provide an inexpensive push switch which can obtain a clear click feeling and a sufficient restoring force. Further, these push switches exhibit the favorable assembling property. Accordingly, it is preferable to adopt the push switch having such a constitution.